Post on 13-Jul-2020
ERGONOMIC SLEEPING BAG SUPPORT Eliana Palumbo
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Acknowledgements
I would like to thank my parents for their financial support and their patience by
putting up with a dining room full of different foams. They were extremely supportive
throughout this whole process and were always there to answer any engineering questions I
had. I would also like to thank Mr. Regele, Mr. Ellis, Ms. Curran, and Mr. Brunner. I would
like to thank them for their guidance throughout the duration of this project because they
were always there to brainstorm with me and help me with anything I needed.
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Table of Contents Acknowledgements ................................................................................................................ 1
Abstract .................................................................................................................................. 4
Literature Review ................................................................................................................... 5
Insomnia ............................................................................................................................. 5
Sleep Debt........................................................................................................................... 6
Sleep Deprivation Impairing Emotional Recognition ........................................................ 6
Sleeping Cycles and REM .................................................................................................. 7
Sleep Number ..................................................................................................................... 8
Spinal Alignment ................................................................................................................ 9
Spinal Displacement Side Effects..................................................................................... 10
Pressure Related Injuries .................................................................................................. 11
Engineering Plan .................................................................................................................. 14
Engineering Problem Statement ....................................................................................... 14
Engineering Goals ............................................................................................................ 14
Procedure Overview ......................................................................................................... 14
Methodology ........................................................................................................................ 15
Materials ........................................................................................................................... 15
Procedure .......................................................................................................................... 15
Results .................................................................................................................................. 19
Conclusions .......................................................................................................................... 20
References ............................................................................................................................ 22
Appendix .............................................................................................................................. 24
Limitations ........................................................................................................................ 24
Assumptions ..................................................................................................................... 24
Raw Data .......................................................................................................................... 25
Engineering Matrix Ranges .............................................................................................. 27
Notes File .......................................................................................................................... 27
Literature Search Parameters ............................................................................................ 27
Knowledge Gaps............................................................................................................... 27
DSM-5 Insomnia and Short Sleep .................................................................................... 28
Medicated and un-medicated kids with ADHD ............................................................... 29
Sleep Deprivation Impairs Recognition of Specific Emotions ......................................... 30
Back Alignment ................................................................................................................ 31
Foams................................................................................................................................ 32
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Different Types of Foam .................................................................................................. 33
Back Alignment 2 ............................................................................................................. 34
Average Lengths of Mattresses and People ...................................................................... 35
Sleep Number Mattress .................................................................................................... 36
Amazon Sleeping Bag Reviews ....................................................................................... 37
Talking with Ms. Curran .................................................................................................. 38
Sleep Cycles ..................................................................................................................... 39
Sleep Rhythms .................................................................................................................. 40
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Abstract
Sleeping bags do not support the spine properly, maximize sleep time, or optimize
sleep quality. A support that is too soft or too hard can cause spinal joint irritation and back
pain. If there are unsupported gaps between the body and the support, pressure points may
begin to form. Other problems, such as a restriction of blood flow and a constriction of
nerves, can arise as a result of a misaligned spine. The purpose of this project was to create an
insert for a sleeping bag that would keep the spine in a neutral position, while evenly
distributing the sleeper's weight. Five different foams were tested, using a pressure sensor to
obtain the contact area, average pressure, and maximum pressure exerted on a model body. A
model spine was also developed to assess whether the foams kept the spine in its neutral
position. The most effective foam was Memory Foam, as determined by the weight and spine
data. Using the foam insert could significantly improve the comfort and support of the
sleeping bag user.
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Literature Review
Insomnia
Insomnia is one of the most widespread health concerns and an estimated 30% to 50%
of the general population has been affected by insomnia. ("Disorders and Treatments:
Insomnia", 2010) Even though insomnia is so common, clinicians are often reluctant to treat
the problem because they have difficulty identifying the cause, they are unfamiliar with some
of the treatment options, or have concerns with pharmacologic treatments. This common
clinical condition can be distinguished by the difficulty of initiating or maintaining sleep.
Insomnia puts the sleeper at risk for impaired function, and the development of other medical
and mental disorders. The causes and observed conditions of insomnia include genetic,
environmental, behavioral, and physiological factors that lead up to hyperarousal. After a
thorough history of sleep behaviors, medical problems, psychiatric problems, common
medications, and a potential record of sleep patterns, insomnia can be diagnosed. If
behavioral treatments cannot be used, then medications should be used for the shortest
amount of time and in the lowest dosage possible. Clinicians are able to diagnose insomnia
because of its effects on function and health; a thorough clinical history is often sufficient to
identify factors that contribute to insomnia. Behavioral treatments should be used when
possible and hypnotic medications are also efficacious but should be carefully monitored.
(Daniel J. Buysse, 2013)
Insomnia disorder with short sleeping periods is the most severe type of insomnia.
The subjects in a recent study were asked to self-report information like insomnia
classification, sleep duration, vascular events, cardiometabolic disease, pain conditions, and
psychiatric symptoms. The researchers found that short sleeping insomniacs were at a higher
risk of myocardial infarction, stroke, diabetes, chronic pain, back pain, anxiety, and
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depression independent of sex, age, and obesity. Cardiometabolic and psychiatric illness
burden was greater for black people with short sleep; black people who experienced sleep
disturbances had a greater risk of health problems than their white peers. (Kalmbach, 2016)
Sleep Debt
Sleep debt is known as the difference between the amount of sleep people get and the
amount of sleep that their individual body requires. The amount of sleep debt accumulates
slowly, and the effects of sleep deprivation vary depending on if the deprivation is short-term
or long-term. Short-term effects include worsened vision, a foggy brain, impaired driving,
and memory problems, while long-term effects include obesity, heart disease, high blood
pressure, strokes, and mood disorders. Because most Americans do not get the sleep their
body requires, they suffer from chronic sleep deprivation and experiencing the corresponding
side effects. Although experts recommend around 8 hours of sleep while the average
American only sleeps 6.9 hours per night. This sleep deficit can be rectified in a few ways:
sleeping an extra 1-2 hours each night over the course of a few months or going to sleep
when tired and waking up naturally. Sleep debt cannot be eliminated by simply sleeping two
hours longer the next day to offset the two hours missed the night before. As the effects of
sleep deprivation dissipate, the body will settle into to a sleep pattern that will improve both
physical and mental capabilities. (Webster, 2008)
Sleep Deprivation Impairing Emotional Recognition
One experiment studied the difference in emotional processing after one night of sleep
deprivation and one night of recovery sleep. Emotional understanding was determined by an
online test that showed the subjects pictures of a man with six different emotional facial cues.
The participants were given the test four times. The participants would see the image, then
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have an unlimited amount of time to click on the emotion label that they thought most
accurately represented the face of the man.
The researchers not only identified that session and emotion type significantly
influenced the data, but they also identified a significant association between the session and
the emotion type. The ability to correctly identify happiness and sadness was reduced after
the subjects were sleep deprived, but the ability to recognize the other four emotions (anger,
surprise, fear, and disgust) did not show a significant difference. For both happiness and
sadness, there was a significant quadratic effect which suggested that sleep deprivation
negatively affected the accuracy judgments of the subjects. A quadratic effect means that the
first time they took the test and the third time they took the test, they were much better at
identifying the emotions, but when they were sleep deprived (second time), they could not
identify the emotions nearly as well; the three times they took the test made a quadratic or U
shape. The accuracy in the identification of the emotions decreased from the baseline to the
sleep deprivation as well as a significant increase from sleep deprivation to recovery. The
findings suggest that during times of compromised emotional capacity due to sleep
deprivation, the brain may reserve recognition resources that are necessary for responding to
threats. These come at the expense of the resources that are available for recognizing less
urgent emotions associated with empathy and social relationships. (Killgore, 2017)
Sleeping Cycles and REM
There are two basic types of sleep that are linked to neuronal activity and specific
brain waves, these include rapid eye movement (REM) sleep and non-REM sleep. All the
stages of non-REM and REM sleep are circled through many times during a usual night.
REM periods grow increasingly longer and deeper towards the morning.
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The first stage of non-REM sleep is the changeover from wakefulness to sleep. This
period is several minutes of relatively light sleep where heartbeat, breathing, and eye
movements begin to slow, and muscles relax with occasional twitches. Brain waves also
begin to slow from their daytime patterns. The second stage of non-REM sleep is a period of
light sleep that precedes deeper sleep. Heartbeat and breathing continue to slow, and muscles
relax even further while body temperature drops, and eye movements stop. Most of the sleep
cycle is taken up by stage 2 sleep than in other sleep stages. The third and final stage of non-
REM sleep is the period of deep sleep that allows the body to feel refreshed the next day.
Heartbeat and breathing begins to slow to their lowest levels during this stage. Muscles are
relaxed, and it may become difficult to awaken the sleeping person. REM sleep is the last
stage and first occurs about 90 minutes after falling asleep; in this stage, eyes move rapidly
from side to side behind closed eyelids. Breathing may become faster and irregular, and heart
rate and blood pressure increase to near waking levels. Almost all dreaming occurs during
REM sleep, but some may occur in non-REM sleep. Arm and leg muscles can become
temporarily paralyzed, and this will prevent the sleeper from acting out their dreams. As one
ages, REM sleep time decreases. ("Brain Basics: Understanding Sleep,” n.d.)
Sleep Number
Mattress companies use this scientific information to ensure the support they are
providing, with their mattresses, promote good sleep patterns. Sleep Number beds are one of
the most famous mattresses because they have a multitude of options that let the consumers
choose every aspect of their product. The Sleep Number Setting allows the users to adjust to
their ideal level of firmness and comfort. Responsive Air Technology can sense the users’
movements and then automatically adjusts the firmness and support to keep them sleeping all
night long. The FlexFit adjustable base allows the users to raise their partner’s head to
alleviate mild snoring. The SleepIQ technology inside the bed is used to track how well the
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user sleeps each night. The Sleep IQ analysis also tells the users their best Sleep Number,
best sleep hours, and connects to the users’ favorite health and wellness apps. Their Sleep
Number allows the user to learn how life affects their sleep and how sleep affects their life.
Most customers love their Sleep Number beds, while some are quite displeased. One
customer complained that his bed was not firm enough and “even with the sleep number set
at 100 [he] still sunk down.” Another customer claimed that “changing settings doesn't
exactly help, and it is making [his] back pain
worse.” Some customers even made jokes like
“I think the "P" stands for pain in P5” when
discussing how back pain seemed to worsen
after using the mattress. (“Sleep Number,”
n.d.)
Spinal Alignment
When sleeping the body is supposed to heal itself and recover from the day. The
muscles and ligaments of the back are supposed to be relaxed and heal themselves while
sleeping. A mattress is supposed to allow the sleeper to wake up feeling rested and free of pain
or soreness. It should support the natural curve of the spine and provide comfort as well. Simple
things can reduce stress on the body and provide targeted support. When sleeping face up, a
pillow under the knees and a pillow for under the head will reduce the stress on the spine, by
supporting the lower back, neck, and shoulders. When sleeping face down, a pillow under the
stomach and pelvis area and either a flat pillow or a pillow under the head can help keep the
spine in better alignment. For side sleepers, a pillow between the knees can prevent the upper
leg from pulling the spine out of alignment while reducing stress on the hips and lower back.
Figure 1. An image showcasing the adjustable base
for the individual settings and a short description of
the Sleep IQ. (Sleep Number, n.d.)
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A pillow under the head and waist should keep the spine straight and in its neutral position.
While moving during sleep, the entire body should move as one unit, avoiding twisting or
turning at the waist to keep the spine and muscles of the back relaxed. (“Good Sleeping
Posture,” n.d.)
A good mattress should conform to the natural curves of the spine. One that is too soft
will allow the lower back to sink too far into the mattress, irritate spinal joints and cause
lower back pain. A mattress that is too firm will have unsupported gaps between the mattress
and the spinal curves. Pressure points, which lead to poor sleep, may begin to develop on the
parts of the body in contact with the mattress. If proper posture is maintained, the spine will
be aligned and not pinch the spinal cord. A person will appear straighter, taller, and more
confident with a strong back that supports their entire body. (“We Know Mattresses,” n.d.)
Spinal Displacement Side Effects
Figure 2. Comparison of mattresses with different
firmnesses, showing the position of the spine on each.
(“We Know Mattresses,” n.d.)
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Sore Muscles- When slouching, the muscles must work harder to keep the spine
stabilized; this can cause tightness and fatigue. Chronic issues may develop from the neck all
the way down to the lower back.
Spinal Curvature- The spine has 3 natural curves that make an ‘S’ shape (Figure 3).
Poor posture can lead to increasing pressure which may cause the natural curves to change
position. If the natural curve changes, it can compromise the spine’s ability to act as a shock
absorber and the person’s ability to stay balanced when standing.
Subluxations- When a vertebra becomes misaligned from the rest of the spine, it
affects the overall strength of the spinal column. When the spine is misaligned, it can also
lead to chronic stress and irritation of both the spine and its surrounding nerves.
Blood Vessel Constriction- If the spine suffers from subluxations and changes to its
curvature, blood vessels can become constricted. Constriction may diminish or cut off blood
supply to muscles, impacting oxygen flow to these muscles and
other areas.
Nerve Constriction- Poor posture often leads to nerve
constriction. As the spine changes shape, the subluxations put
pressure on the surrounding spinal nerves. Pinched nerves can
cause not only neck and back pain but also pain in other
seemingly unrelated areas of the body. (“We Know
Mattresses,” n.d.)
Pressure Related Injuries
Figure 3. The 3 natural curves
of the spine.
(“We Know Mattresses,” n.d.)
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If pressure is reduced on one body part, pressure will increase elsewhere on the body.
The goal any support is to obtain the best pressure redistribution possible, but, all the pressure
may never be taken away. Pressure ulcers begin to develop when the capillaries supplying the
skin and tissues are compressed enough to impede perfusion; this may ultimately lead to
tissue necrosis. The normal blood pressure within capillaries ranges from 20 to 40 mmHg,
where 32 mmHg is considered to be the average. Keeping external pressures at less than 32
mmHg should be sufficient for preventing the development of pressure ulcers. Capillary
blood pressure may be less than 32 mmHg in ill patient, so, even lower applied pressures may
be enough to induce ulceration. Pressure ulcers can develop in as little as 2 to 6 hours.
(Hughes, 2008)
The Braden Scale is designed for adults and consists of 6 subscales: sensory
perception, moisture, activity, mobility, nutrition, and friction and shear. It is based on the
linking of the clinical situations to the intensity and duration of pressure. The scores on the
Braden Scale range from a 6 (high risk) to 23 (low risk); 18 is the cutoff score for the onset of
pressure ulcer risk. (Hughes, 2008)
The buttocks, shoulders, and torso are the heaviest parts of the body, while the head,
knees, and feet are lightest. The average person can move as much as 75 times a night, every
6-8 minutes, even during the deepest phase of sleep. To prevent problems from developing
from prolonged pressure, such as reduced blood flow, the body will begin to move when
sleeping as a protective mechanism. A surface that offers pressure-point relief, by distributing
the weight, will reduce tossing and turning throughout the night; if too much pressure is not
being exerted, the body will not feel the need to move as frequently. (“Pressure Mapping &
Your Mattress,” 2017)
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During sleep, an ischemia (an inadequate blood supply to an organ or part of the
body) may arise. The ischemic event generates metabolic substances that stimulate nerves,
which will cause the person to change his or her posture before it becomes painful. When
sleeping on a surface that is too firm, the body weight will not be distributed homogenously,
and the contact area will be reduced. This reduction in contact area will result in increased
pressure and shear forces on the skin and the underlying soft tissues; blood supply may be
reduced or even stopped due to the deformation of the tissues. Capillary arteriolar pressure
should vary between 3.3 and 4.6 kPa (25 and 35 mmHg), while pressure in the venules
approximates to 1.6 kPa (12 mmHg). Critical pressure however, is considered to be around 4
kPa (30 mmHg). The combined effect of time and intensity may result in the development of
decubitus ulcers. Most ulcers occur in people who stay in bed for long periods of time,
especially when they cannot move themselves or be moved because of an injury (Haex,
2005).
Figure 4. 2D pressure distribution on a
mattress. (“Neurobiology of Sleep,”
2017)
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Engineering Plan
Engineering Problem Statement
Air mattresses and sleeping bags are uncomfortable because they do not support the
spine properly, maximize sleep time, or optimize sleep quality.
Engineering Goals
The goal of this project is to create a foam insert for preexisting sleeping bags that
will minimize spinal displacement, distribute weight evenly, be cost efficient, and have a
quick recovery time.
Procedure Overview
Five different foams were tested to see which was the best when it came to weight
distribution. A sheet of foam was placed on a table, followed by the Sensor Edge pressure
sensor so that the edges were not tucked under the foam, but were laid out. Then, a Barbie
was placed in the center of the sensor, without letting any part of the doll fall over the edge.
Three 2.5 lb. circular weights were put on top of the legs of the Barbie, her chest, and her
pelvic area to weight her down. The three weights were positioned so that they were lined up
with the center line of the Barbie’s body, so they would not tip over, touch the sensor, or
cause an uneven force on the different sides of the doll’s body. A recording of the trial on
Measure X was started immediately after the last weight was put on. After thirty minutes of
recording the doll, it would be stopped and saved. The percent contact area, average pressure,
and maximum pressure were recorded. The last setting was the table, where the past steps
were repeated, except there was no foam placed in-between the table and the sensor. There
were 5 trials for the 4 different foams and the table.
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Methodology
Materials
Materials From Cost
EverFlex V34 Medium-Firm Foam foamorder.com $5.98
EverFlex V44 Firm Foam foamorder.com $5.98
DuraFlex D30 Medium-Firm Foam foamorder.com $3.50
Memory Foam foamorder.com $11.52
Latex Foam Jordan’s n/a
Barbell Weights (3) Mass Academy n/a
Sensor Edge Pressure Mat Easter Seals n/a
Measure X Software on HP Computer Easter Seals n/a
ABS Pipe Home Depot $4.52
O Rings Home Depot $4.97
Clear PVC Hose Home Depot $4.78
Procedure
A 12” x 12” x 2” sheet of EverFlex V34 Medium-Firm, EverFlex V44 Firm, DuraFlex
D30 Medium-Firm, Latex Foam and Memory Foam were tested to see which was the best
able to distribute weight. First, a foam sheet was placed on a blank table, followed by the
Sensor Edge pressure sensor. The sensor was carefully placed so that the edges were not
tucked under the foam. Second, a Barbie was placed in the center of the sensor, without
letting any part of the doll fall over the edge. Additionally, three 2.5 lb. circular weights were
put flat on top of the doll, where one weight had a slightly larger diameter than the other two.
The weight with the largest diameter was put on top of the legs of the Barbie, where the front
edge was lined up with its ankles and the back edge landed on its mid-thigh. The second
weight was put on its upper body where the front edge reached its belly button and the back
edge landed on its hairline. The last weight was put on top of the other two weights, so the
center aligned with the pelvic area. The three weights were positioned so that they were lined
up with the center line of the Barbie’s body, so they would not tip over, touch the sensor, or
Table 1. The materials used in this project and where they were acquired.
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cause an uneven force on the different sides of the doll’s body. If when placing the weights
on top of the Barbie, one of the weights were to fall off and cause an impression in the foam,
everything would be taken off the foam and after three minutes passed, the process would
start again. If the placement was successful, a recording of the trial on Measure X was started
immediately after the last weight was positioned.
After thirty minutes of recording the doll, the video would be stopped and saved. The
weights were left off the foam for five minutes before another test began to give the foam
time to recover. To access the data, the “Print” icon was chosen and then a picture (Figure 6.)
would be shown displaying the contact area, average pressure, and maximum pressure. This
function only shows the data where the curser is in the recording, so the beginning
information would be written down, then the video was fast forwarded to the end of the
session. That data was recorded using the same method. The last setting was a plain table,
where the past steps were repeated, except there was no foam placed in-between the table and
the pressure sensor. This was taken to see how the doll’s weight would be distributed with no
Figure 5. Picture of the Barbie on the foam and sensor with the
weights on top of it.
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support at all. The number of trials run for the 5 different foams and the table was 5 because
of the longer time frame of each trial.
To analyze the data, a two-tailed paired t-test was run to see if there was a difference
in the averages of the data before the 30 minutes and after the 30 minutes had passed. A
paired t-test was chosen because it can be used to compare two samples in which
observations in one can be paired with the observations in the other. An example of a testing
comparison includes the 5 data points for the contact area of Foam 1 before the time and the 5
data points for the contact area of Foam 1 after the time frame had passed. This process was
repeated for the contact area, average pressure, and the maximum pressure for each foam.
Furthermore, the averages of the before and after for each section were also compared to see
how much the averages changed after the time frame passed.
Figure 6. An image of what the “Print”
button displayed.
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To test the foam’s recovery time, three circular barbells where placed on top of a sheet
of foam. The weights were left there for 5 minutes each and when the 5 minutes ended, the
weights were immediately taken off the foam. As soon as they were removed a stopwatch
started and when the foam returned to its original neutral position the timer was stopped. If a
foam returned to its original position as the weights were removed, then the foam was given a
recovery time of 0 seconds.
For spinal displacement testing, a model spine was made. 12, 1-inch long pieces were
cut out of PVC pipe that had a diameter of ¾ inch to resemble T2-T13 of the spine. L1-L6
were made from 6, 1 ½ inch long pieces of PVC pipe with a diameter of 1 inch. The 12
pieces were put onto a rubber hose with an outside diameter of ¾ inch. Each piece was
separated by a rubber O-Ring with a ¾ inch diameter. The O-Ring was used to provide space
in between the spinal pieces and to resemble discs found in the spine. After the 12 were put
on then the 6 larger pieces were put on the hose with 2 O-Rings placed in between each.
After all the pieces were on, the ends of the hose were cut off. A copper bar was left inside of
the hose overnight, so it would straighten from its curved shape. Refer to Figure 7 to find the
final model.
To test the spinal displacement of the different foams, the model spine and 2 barbell
weights were used. First, the desired spinal curve was traced on a large piece of paper. The
Figure 7. A smaller model spine made of PVC pipes, a hose, and O-Rings.
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model was then bent to that shape for 30 seconds. The top side of the beginning shape was
traced on the sheet of paper. Then, the spine was laid diagonally on the foam so the whole
model would be touching it. One weight was then laid on T6 and one on L4. To ensure that
the weights would not fall to one side, 4, 1-inch long pieces were cut out of PVC pipe and
were used to support the weights on both sides. After the spine was set in place, a timer for
10 minutes was started. When the time was over, the weights were taken off and the spine
was traced in a different color on top of its starting curve. This process was repeated five
times for each foam. After a test was complete the displacement would then be calculated.
Every inch, the vertical distance from the original curve to the final curve was measured; all
the distances were totaled, and that number was the test’s total displacement.
Results
Contact
Area
Before
(%)
Contact
Area
After
(%)
Average
Pressure
Before
(mmHg)
Average
Pressure
After
(mmHg)
Maximum
Pressure
Before
(mmHg)
Maximum
Pressure
After
(mmHg)
Foam 1 4.45 5.49 27.54 30.50 186.05 234.55
Foam 2 4.45 6.07 16.94 20.28 94.32 122.55
Foam 3 2.87 3.38 32.47 37.14 170.95 216.38
Foam 4 3.87 5.31 16.98 18.86 113.56 152.65
Foam 5 5.53 6.35 17.94 23.51 91.22 138.48
The summary data in Table 2. shows the averages of each foam’s subsections. Foam 5
had the highest contact area percentage from 5.53 to 6.35%, while Foam 3 averaged between
2.87 to 3.38%, which was the lowest. Foam 4 had the lowest average pressure ranging from
16.98 mmHg to 18.86 mmHg, opposed to Foam 3 which had the highest that ranged from
Table 2. Summary data of the contact area, average pressure, and maximum pressure
before and after the time interval for each foam.
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32.47 mmHg to 37.14 mmHg. Foam 2 had the lowest maximum pressure which ranged from
94.32 mmHg to 122.55 mmHg, while 186.05 mmHg to 234.55 mmHg was the highest
belonging to Foam 1. On average, the contact area percentage increased by 1.09% after the
30 minutes. The average pressure also increased by 3.68 mmHg, while the maximum
pressure increased by 41.70 mmHg. When comparing the before and afters of each foam
through a paired t-test, there was a resulting p-value of less than 0.05 for every test.
For the recovery times, Foam 2 had an average time of 12.18 seconds. The 4 other
foams all had an average recovery time of 0 seconds. This meant that when the weights were
removed, the foam instantly went back to its neutral position.
The foam with the lowest spinal displacement was Foam 2 with an average of 1.59
inches. While the foam with the greatest average displacement was Foam 5 at 2.88 inches.
Foam 1 averaged 2.67 inches, Foam 3 averaged 2.20 inches, and Foam 4 averaged 2.80
inches.
Conclusions
Criteria Maximum Points Foam 1 Foam 2 Foam 3 Foam 4 Foam 5
Low Spinal Displacement 5 2 4 3 2 2
Quick Recovery Time 2 2 1 2 2 2
Low Cost 3 2 1 2 3 2
High Contact Area 5 4 5 1 4 5
Low Average Pressure 5 2 4 1 4 3
Low Maximum Pressure 4 1 4 1 3 4
Total 24 13 19 10 18 18
Percent 100 54 79 42 75 75
Based on the chosen criteria, the best foam would have the highest total percentage
out of the points possible. The foams were given a number for each criterion based on a
Table 3. Engineering Matrix to decipher which was the best foam based on the criteria.
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predetermined scale of values that ranked it in comparison to the others. The points were then
totaled, and a percentage for each foam was displayed.
Foam 2, which was memory foam, was overall the best out of the 5 because it
received the maximum points for contact area, average pressure, and maximum pressure.
Even though it was the most expensive and was the only foam to have a recovery time, it was
still the best because of the criteria’s ranking. Foam 4 tied for second place with Foam 5
earning the maximum number of points in recovery time and cost. Foam 5 earned the
maximum number of points in recovery time and contact area. Foam 3 had the lowest
percentage and only earned the maximum number of points in recovery time.
If this testing were to continue, there are many possible future extensions to this work.
Extensions could include: testing full sheets of foam, making a prototype that will provide
support under the insert made from different pipes or foams with different densities, making
the insert able to roll up and store easily, and testing competitor’s inserts using the same
techniques. When testing the future extensions, using people would be preferable because it
would make the quality of the research better. If humans were not able to be used, more
advanced anatomical models would be tested.
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=onepage&q&f=false
Hughes, R. (2008). Patient Safety and Quality: An Evidence-Based Handbook for Nurses.
Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK2650/
Kalmbach, D. A., Pillai, V., Arnedt, J. T., & Drake, C. L. (2016, December 01). DSM-5
Insomnia and Short Sleep: Comorbidity Landscape and Racial Disparities. Retrieved
September 16, 2017, from
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103798/#!po=12.2951
Killgore, W. (2017). Neurobiology of Sleep and Circadian Rhythms. (n.d.). Retrieved
September 27, 2017, from https://www.journals.elsevier.com/neurobiology-of-sleep-
and-circadian-rhythms
Palumbo 23
McMaster-Carr. (n.d.). Retrieved October 7, 2017, from
https://www.mcmaster.com/#standard-foam-sheets/=19r1gng
Pressure Mapping & Your Mattress. (2017, October 16). Retrieved November 12, 2017, from
http://restonic.com/blog/pressure-mapping-and-your-mattress-1975
Rest 'N' Roll Easy Store Single Camping Sleeping Pad with Carrying Straps. (n.d.). Retrieved
October 17, 2017, from https://www.amazon.com/Single-Camping-Sleeping-
Carrying-Straps/product-
reviews/B00EMJVPIQ/ref=cm_cr_dp_d_hist_1?ie=UTF8&filterByStar=one_star&re
viewerType=all_reviews-filter-bar
Sleep Number Site | Adjustable Beds, Memory Foam Mattresses, Kids Beds, Pillows &
More. (n.d.). Retrieved October 17, 2017, from https://www.sleepnumber.com/
Types of Foam - An In-Depth Look at Different Foam Mattresses. (2017, September 30).
Retrieved October 15, 2017, from https://www.thesleepjudge.com/types-of-foam/
Webster, M. (2008, May 6). Can You Catch Up on Lost Sleep? Retrieved August 28, 2017,
from https://www.scientificamerican.com/article/fact-or-fiction-can-you-catch-up-on-
sleep/
Palumbo 24
Appendix
Limitations
1. Weight Distribution tests took 30 minutes each so the number of times the test could
be run was limited to 5 per foam.
2. Human testing was not allowed, so dolls and models had to be used to simulate
human bodies.
3. Funding was limited so only a few foams could be bought.
Assumptions
1. Complications like subluxations and the formation of pressure points arise because of
the support the body is lying on and not the body itself.
2. Smaller models of the human body are representative of larger bodies.
3. A Barbie has a similar enough body shape to a human, to be used to simulate a human
lying on foam.
4. A model spine is representative of a human spine when laid on top of the foam.
5. The Sensor Edge gave accurate readings pertaining to the contact area, average
pressure, and maximum pressure of the doll.
6. The foams received from foamorder.com were the foams that were advertised and
ordered online.
7. A model spine made from ABS piping, O-Rings, and Clear PVC piping resemble the
way a human spine moves.
Palumbo 25
Raw Data
Foam 1 Foam 2
Before After Before After Contact Area (%) 4.20 5.86 Contact Area (%) 2.93 5.18
4.30 5.27 4.20 5.27
4.39 5.76 4.69 6.54
4.49 4.79 4.96 6.54
4.88 5.76 Diff 5.47 6.84 Diff
Average 4.45 5.49 1.04 Average 4.45 6.07 1.62
Before After Before After Average Pressure 18.01 22.96 Average Pressure 14.48 16.75
(mmHg) 27.03 31.31 (mmHg) 15.96 18.48
27.25 31.07 16.77 18.74
30.60 32.00 18.36 25.47
34.83 35.15 Diff 19.14 21.96 Diff
Average 27.54 30.50 2.95 Average 16.94 20.28 3.34
Before After Before After Maximum Pressure 86.36 124.10 Maximum Pressure 68.77 87.39
(mmHg) 143.75 206.32 (mmHg) 87.39 108.59
176.33 207.87 99.8 156.16
250.79 314.91 106.52 127.21
273.03 319.57 Diff 109.11 133.41 Diff
Average 186.05 234.55 48.50 Average 94.318 122.55 28.23
Foam 3 Foam 4
Before After Before After Contact Area (%) 2.64 3.13 Contact Area (%) 2.73 4.69
2.73 3.52 2.83 4.88
2.73 3.22 3.91 5.57
3.03 3.52 4.88 5.57
3.22 3.52 Diff 4.98 5.86 Diff
Average 2.87 3.38 0.51 Average 3.87 5.31 1.45
Before After Before After Average Pressure 24.75 29.62 Average Pressure 15.06 18.31
(mmHg) 27.82 34.59 (mmHg) 15.31 17.70
32.85 37.39 15.37 18.53
38.01 43.15 19.03 18.51
38.93 40.97 Diff 20.13 21.27 Diff
Average 32.47 37.14 4.67 Average 16.98 18.86 1.88
Table 4. Raw weight distribution data.
Palumbo 26
Foam 5
Before After Contact Area (%) 3.81 4.30
5.66 6.93
5.76 6.93
6.15 6.84
6.25 6.74 Diff
Average 5.53 6.35 0.82
Before After Average Pressure 16.70 21.41
(mmHg) 16.73 22.16
17.58 24.56
19.06 25.60
19.65 23.83 Diff
Average 17.94 23.51 5.57
Before After Maximum Pressure 69.29 113.76
(mmHg) 81.18 116.86
96.18 123.07
103.94 197.02
105.49 141.69 Diff
Average 91.22 138.48 47.26
Spinal Displacement Data (in)
Foam 1 Foam 2 Foam 3 Foam 4 Foam 5
2.625 2.125 2.500 2.438 3.063
4.438 1.063 2.063 2.063 2.500
1.688 1.625 2.188 3.500 2.438
1.938 1.563 2.063 3.188 3.500
Average 2.672 1.594 2.203 2.797 2.875
Before After Before After Maximum Pressure 85.32 117.90 Maximum Pressure 64.64 86.87
(mmHg) 155.13 197.02 (mmHg) 89.98 143.75
158.75 217.18 97.21 130.83
207.36 250.79 117.90 178.40
248.21 298.99 Diff 198.05 223.39 Diff
Average 170.95 216.38 45.42 Average 113.56 152.65 39.09
Table 5. Raw spinal displacement data.
Palumbo 27
Engineering Matrix Ranges
Notes File
Literature Search Parameters Database/ Search Engine Keywords
WPI Summon Sleep, insomnia
WPI Summon Medicated sleep
WPI Summon Sleep deprivation
Google Sleeping posture
Google Mattress foams
Google Spine alignment, sleep
Google Bed lengths
Google Amazon, sleeping bag
WPI Summon Average height
Google Sleep Number
Knowledge Gaps Knowledge Gap Resolved by Information is Located
How does artificial light affect
sleeping habits?
Reading Sleep Abstract Doc Notes
What foams will be the best
material?
Reading Foams
Criteria Maximum
Points 5 Points 4 Points 3 Points 2 Points 1 Point
Spinal
Displacement 5 0-1.5 inches 1.5-2 inches 2-2.5 inches 2.5-3 inches 3 inches+
Recovery
Time 2 n/a n/a n/a 0-10 seconds
10
seconds +
Cost 3 n/a n/a 0-5$ 5-10$ 10$ +
Contact Area 5 5 % + 4.5-5% 4-4.5% 3.5-4% 0-3.5%
Average
Pressure 5 0-15 mmHg 15-20 mmHg 20-25 mmHg 25-30 mmHg
30
mmHg +
Maximum
Pressure 4 n/a 0-120 mmHg
120-150
mmHg
150-180
mmHg
180
mmHg +
Table 6. A display of the ranges that were used to score the different foams in the engineering matrix.
Palumbo 28
How will I decipher between
the foams?
Talking with Mrs. Curran Logbook
How will I see the position of
the spine?
Talking with Curran/
brothers doctor?
Talking with Mr. Brunner, Mr.
Ellis, and Mr. Regele
Source
Title DSM-5 Insomnia and Short Sleep
Source
Citation Kalmbach, D. A., Pillai, V., Arnedt, J. T., & Drake, C. L. (2016, December 01). DSM-
5 Insomnia and Short Sleep: Comorbidity Landscape and Racial Disparities.
Retrieved September 16, 2017, from
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5103798/#!po=12.2951
Source
found by
Searched “insomnia” in the US National Library of Medicine
Source
Type
Journal Article
Keywords DSM-5, insomnia, racial disparities, comorbidity
Summary -examined the roles of insomnia and short sleep in racial disparities in disease burden
black and white Americans
Reason
for
Interest
Wanted to learn about insomnia cause/effect
Notes -insomnia disorder with short sleep is the most severe phenotype of insomnia
-subjects self-reported insomnia classification, sleep duration, vascular events,
cardiometabolic disease, pain conditions and psychiatric symptoms
-short sleeping insomniacs were at a higher risk for myocardial infarction, stroke,
diabetes, chronic pain, back pain, anxiety, and depression independent of sex, age, and
obesity
-cardiometabolic and psychiatric illness burden was greater for blacks with short sleep
-blacks with sleep disturbances have a greater risk of health problems than whites
Questions Why are black people more susceptible to health problems than white people?
Palumbo 29
Source
Title Medicated and un-medicated kids with ADHD
Source
Citation
Cockcroft, K., Ashwal, J., & Bentley, A. (2009, November). Sleep and daytime
sleepiness in methylphenidate medicated and un-medicated children with attention-
deficit/hyperactivity disorder (ADHD). Retrieved September 16, 2017, from
file:///C:/Users/Eliana/Downloads/49043-65120-1-PB.pdf
Source
found by
Searching “medicated sleep” in WPI library for journal articles
Source
Type
Journal Article
Keywords methylphenidate, ADHD, daytime sleepiness
Summary Study which compared the perceived levels of daytime sleepiness and prevalence of
sleep disorders in medicated and un-medicated children with ADHD.
Reason
for
Interest
Wanted to study differences between medicated and un-medicated sleep
Notes -two groups: one taking methylphenidate twice daily and the other taking no meds
-the kids and their parents both rated their levels of sleepiness at three points in the day
-significantly higher levels of daytime sleepiness was reported for the un-medicated
group around 1 to 3 o’clock compared to the medicated group
-there was a significant increase in sleepiness a few hours after taking the medicine
which could have an impact on their learning
-the medication had a significant effect because it reduced the level of sleepiness for the
duration of the action of it
Questions n/a
Palumbo 30
Source
Title Sleep Deprivation Impairs Recognition of Specific Emotions
Source
Citation
Neurobiology of Sleep and Circadian
Rhythms. (n.d.). Retrieved September 27,
2017, from
https://www.journals.elsevier.com/neurobio
logy-of-sleep-and-circadian-rhythms
Source
found by
Searching in WPI Summon.
Source
Type
Journal Article
Keywords Deprivation, recognition, emotions
Summary -studied the difference in emotional processing after one night of sleep deprivation and
one
night of recovery sleep. The difference in responses for the emotional detections was
determine
d by an online test that showed the subjects pictures of a man with different facial cues.
The researchers found that, although both genders were equally accurate following sleep
deprivation, subjects of different genders recognized different emotions. The ability to
correctly identify happiness and sadness was reduced after the subjects were sleep
deprived but the ability to recognize the other four emotions (anger, surprise, fear, and
disgust) did not show a significant difference.
Reason
for
Interest
How does sleep deprivation affect the brain?
Notes
Questions n/a
Subjects underwent 8 hours of sleep, 61 hours of wakefullness and finally 12
hours of sleep.
After sleep, wakefulness and the rest day, they were tested to see if there was a
difference in how sleep deprivation affected
emotional recognition.
The test consisted of morphed expression photos of 2 of the 6
emotions and tested the subjects ability to
recognize different emotions.
The label order was randomized and the
picture was shown for 5 seconds. These were done
to try to reduce the variablity and minimize
bias.
The data was then analyzed by the sex of the subject, the test session,
their reaction time, and the emotion category.
Palumbo 31
Source
Title Back Alignment
Source
Citation
Good Sleeping Posture Helps Your Back. (n.d.). Retrieved October 5, 2017, from
https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=1&Content
ID=4460
Source
found by
Google Search
Source
Type
Website
Keywords sleeping, posture
Summary -keep your ears, shoulders, and hips aligned
- either pillows or the mattress itself should fill the gaps between your body and the
mattress
Reason
for
Interest
How should the back be positioned?
Notes -muscles and ligaments of your back relax and heal themselves while you sleep
-mattress that's right for you lets you wake up feeling rested and free of pain or soreness
-choose a mattress that provides support for the natural curves of your spine and is
comfortable
-sleeping on your back: a small pillow under your knees-> reduce stress on your spine
and support the natural curve in your lower back, pillow for your head should support
the natural curve of your neck, and your shoulders
-sleeping on your stomach: a pillow under the stomach and pelvis area can help to keep
the spine in better alignment, a pillow for your head should be flat, or sleep without one
-sleeping on your side, a pillow between your knees will prevent the upper leg from
pulling the spine out of alignment and reduce stress on the hips and lower back, pull
knees up slightly toward the chest, pillow for your head should keep your spine straight,
pillow under your waist too
-do not twist or bend at the waist, move your entire body as one unit, keep your belly
pulled in and tightened, and bend your knees toward the chest when you roll
Questions n/a
Palumbo 32
Source
Title Foams
Source
Citation
McMaster-Carr. (n.d.). Retrieved October 7, 2017, from
https://www.mcmaster.com/#standard-foam-sheets/=19r1gng
Source
found by
Suggested by Mrs. Curran
Source
Type
Website
Keywords Density, texture, resiliency, specifications
Summary A website that allows me to put in a specific type of foam and it tells me: prices,
material, shape, thickness, size, colors, and the pressure to compress the foam, temp
range, etc.
It gives a short summary of the foam, talking about the compression recovery time, cell
construction and environmental limitations.
Reason
for
Interest
Where can I find the foams properties?
Notes
Questions n/a
Palumbo 33
Source
Title Different Types of Foam
Source
Citation
Types of Foam - An In-Depth Look at Different Foam Mattresses. (2017, September
30). Retrieved October 15, 2017, from https://www.thesleepjudge.com/types-of-foam/
Source
found by
Google Search
Source
Type
Website
Keywords Polyurethane, memory foam, gel, Evlon
Summary For each type of foam, it mentions common places you can find it, what it is, common
customer complaints, broad pricing, temperature regulation, etc.
Reason
for
Interest
Which foams will I test?
Notes Consequences of not getting enough sleep include: obesity, hypertension, diabetes, mood
disorders, heart disease, and shortened life expectancy
Different Types of Foams: Polyurethane Foam, Traditional Memory Foam, Open Cell
Memory Foam, Gel Memory Foam, Gel Foam, Reflex Foam, Convoluted Foam and
Evlon
Questions n/a
Palumbo 34
Source
Title Back Alignment 2
Source
Citation
(n.d.). Retrieved October 13, 2017, from
http://www.weknowmattresses.com/2012/02/proper-spinal-alignment/
Source
found by
Google Search
Source
Type
Website
Keywords Spinal alignment, nervous system, posture
Summary Proper spinal alignment: a good mattress will conform to the spines natural curves and
keep your spine in proper alignment, a mattress that is too soft allows the lower back to
sink too far into the mattress, irritating spinal joints and causing lower back pain, a
mattress that is too firm leads to unsupported gaps between your bodies curves and the
mattress., pressure points develop on those parts of your body in contact with the
mattress- leading to poor sleep
Reason
for
Interest
What is the proper posture for sleeping? What can happen if posture is bad?
Notes -spend 1/3 of your life in bed
-proper posture: spine is aligned, not pinching spinal cord,
appear straight, taller, and confident and the back is strong
and supports the rest of the body properly.
- Side effects of poor spinal alignment include:
Sore Muscles– If you slouch, your muscles must work
harder to keep your spine stabilized, which can cause
tightness and fatigue. Chronic issues may develop from
your neck all the way to your lower back.
Spinal Curvature– Your spine has 3 natural curves that
make and ‘S’ shape (4 if you include the non-moving
curve at the base of the spine). Poor posture can lead to
pressure, influencing those curves to change position. If
the natural curve changes, it compromises the spines
ability to act as a shock absorber and for you to keep your
balance.
Subluxations– when a vertebra becomes misaligned from the rest of the spine, which
affects the overall strength of your spinal column. This can also lead to chronic stress
and irritation of the spinal column and surrounding nerves.
Blood Vessel Constriction– If your spine begins to suffer from Subluxations and
changes to its curvature, your blood vessels can become constricted- diminishing or
cutting off blood supply to muscles, which impacts oxygen flow to these muscles and
other areas.
Nerve Constriction– Bad posture often leads to nerve constriction. Subluxations put
pressure on the surrounding spinal nerves. Pinched nerves cause not only neck and back
pain, but also pain in other seemingly unrelated areas of your body.
Questions n/a
Palumbo 35
Source
Title Average Lengths of Mattresses and People
Source
Citation
-National Center for Health Statistics. (2017, May 03). Retrieved October 3, 2017, from
https://www.cdc.gov/nchs/fastats/body-measurements.htm
-Mattress Size Chart. (n.d.). Retrieved October 3, 2017, from
http://www.sleeptrain.com/mattress-size-chart/education-mattress-size-chart.html
Source
found by
Google Search
Source
Type
Website
Keywords National, height,
Summary Twin beds are normally 39 inches by 74 inches and US male average height is 69.2
inches while the female average height is 63.7 inches.
Reason
for
Interest
How long should I make the mattress/insert?
Notes
Questions n/a
Palumbo 36
Source
Title Sleep Number Mattress
Source
Citation
Sleep Number Site | Adjustable Beds, Memory Foam Mattresses, Kids Beds, Pillows
& More. (n.d.). Retrieved October 17, 2017, from https://www.sleepnumber.com/
Source
found by
Google Search
Source
Type
Website
Keywords SleepNumber, SleepIQ
Summary SleepNumber: lets you adjust your idea of comfort->firmness
SleepIQ: The Sleep Number bed with SleepIQ technology inside tracks how well you
sleep each night, giving you personal insights into your sleep. Tells you your best
SleepNumber, best sleep hours for you and it even connects to your favorite health and
wellness apps, so you'll learn how life affects your sleep and how sleep affects your
life.
Reason for
Interest
What makes this such a good bed? Why the high price tag?
Notes For kid’s beds: parent can track the quality and quantity of the child’s sleep and turn
lights off remotely. They also have a head-tilt option and soft under bed lighting that
turns on when the child gets up at night.
Questions n/a
Palumbo 37
Source
Title Amazon Sleeping Bag Reviews
Source
Citation
Rest 'N' Roll Easy Store Single Camping Sleeping Pad with Carrying Straps. (n.d.).
Retrieved October 17, 2017, from https://www.amazon.com/Single-Camping-Sleeping-
Carrying-Straps/product-
reviews/B00EMJVPIQ/ref=cm_cr_dp_d_hist_1?ie=UTF8&filterByStar=one_star&revi
ewerType=
all_reviews-filter-bar
Source
found by
Google Search
Source
Type
Website
Keywords Sleeping bag, reviews, cheap
Summary This pad was made
to go inside or under
a sleeping bag so
provide support.
Many customers did
not like it and said
that it was cheap and
did not provide
comfort.
Reason for
Interest
What is wrong with sleeping bags/ pads today?
Notes “Thinner than a yoga mat,” “sleeping on a paper towel will be just as good,” “it's very
thin and lightweight,
used it one time ripped that same day...it is a very lightweight Styrofoam
mat,” “you will feel every rock beneath you, assuming it doesn't
disintegrate after an hour of use,” and “No cushion or insulation from cold
at all. Might work as a cheap yoga mat or ground cover if you are going to
the beach or park but not for camping.”
Questions n/a
Palumbo 38
Source
Title Talking with Ms. Curran
Source
Citation
10/25/17
Source
found by
Talking
Source
Type
Speech
Keywords Sleeping pad, pressure sensors, clay, weights
Summary Talk to people.
Reason for Interest Had some questions about how I will get data.
Notes -observe how and how much it compresses
-will it compress over time?
-video tape it with either the
-visit Easter Steals on Main Street in Worcester, mat with numerical and
heat labels that changes colors
-are there places that everyone will need extra support even though people
are different sizes?
-will it be adjustable?
-make a possible “person” out of clay, wires, and weights to stimulate a
real person and spine sleeping on the pad
-reach out to the sleep clinic and ask questions about the project and spinal
positions
-test the different stresses and compression properties
-some sort of website that shows the normal proportions of the body (med
or art websites?) ask Mr. Brunner??
->histogram of the average qualities (human factors and anthropometrics)
-ask previous senior about the drop tests with pressure sensors
-make a list of things that I want it to do, what are some deal breakers if I
was a customer going to use it?
Questions n/a
Palumbo 39
Source
Title Sleep Cycles
Source
Citation
Brain Basics: Understanding Sleep. (n.d.). Retrieved November 26, 2017, from
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-
Sleep#dreaming
Source
found by
Searching REM Sleep into google.
Source
Type
Website
Keywords REM, tips
Summary There are four different stages of sleeping that are broken up into two types (non-REM
sleep and REM sleep). There are also some simple things that you can do to increase
the chance of having a good night’s sleep.
Reason
for
Interest
Need more background on sleep itself
Notes Tips for good nights sleep: Set a schedule – go to bed and wake up at the same time
each day.
Exercise 20 to 30 minutes a day but no later than a few hours before going to bed.
Avoid caffeine and nicotine late in the day and alcoholic drinks before bed.
Relax before bed – try a warm bath, reading, or another relaxing routine.
Create a room for sleep – avoid bright lights and loud sounds, keep the room at a
comfortable temperature, and don’t watch TV or have a computer in your bedroom.
Don’t lie in bed awake. If you can’t get to sleep, do something else, like reading or
listening to music, until you feel tired.
Sleep Stages:
Stage 1 non-REM sleep is the changeover from wakefulness to sleep. During this short
period (lasting several minutes) of relatively light sleep, your heartbeat, breathing, and
eye movements slow, and your muscles relax with occasional twitches. Your brain
waves begin to slow from their daytime wakefulness patterns.
Stage 2 non-REM sleep is a period of light sleep before you enter deeper sleep. Your
heartbeat and breathing slow, and muscles relax even further. Your body temperature
drops, and eye movements stop. Brain wave activity slows but is marked by brief bursts
of electrical activity. You spend more of your repeated sleep cycles in stage 2 sleep
than in other sleep stages.
Stage 3 non-REM sleep is the period of deep sleep that you need to feel refreshed in
the morning. It occurs in longer periods during the first half of the night. Your
heartbeat and breathing slow to their lowest levels during sleep. Your muscles are
relaxed, and it may be difficult to awaken you. Brain waves become even slower.
REM sleep first occurs about 90 minutes after falling asleep. Your eyes move rapidly
from side to side behind closed eyelids. Mixed frequency brain wave activity becomes
closer to that seen in wakefulness. Your breathing becomes faster and irregular, and
your heart rate and blood pressure increase to near waking levels. Most of your
dreaming occurs during REM sleep, although some can also occur in non-REM sleep.
Your arm and leg muscles become temporarily paralyzed, which prevents you from
acting out your dreams. As you age, you sleep less of your time in REM sleep. Memory
consolidation most likely requires both non-REM and REM sleep.
Questions n/a
Palumbo 40
Source
Title Sleep Rhythms
Source
Citation
Brain Basics: Understanding Sleep. (n.d.). Retrieved November 26, 2017, from
https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Understanding-
Sleep#dreaming
Source
found by
Searching REM Sleep into google.
Source
Type
Website
Keywords Homeostasis, circadian rhythms
Reason
for
Interest
Learning more about sleep patterns and rhythms
Notes Circadian rhythms direct a wide variety of functions from daily fluctuations in
wakefulness to body temperature, metabolism, and the release of hormones. They
control your timing of sleep and cause you to be sleepy at night and your tendency to
wake in the morning without an alarm. Your body’s biological clock, which is based on
a roughly 24-hour day, controls most circadian rhythms. Circadian rhythms synchronize
with environmental cues (light, temperature) about the actual time of day, but they
continue even in the absence of cues.
Sleep-wake homeostasis keeps track of your need for sleep. The homeostatic sleep
drive reminds the body to sleep after a certain time and regulates sleep intensity. This
sleep drive gets stronger every hour you are awake and causes you to sleep longer and
more deeply after a period of sleep deprivation.
Factors that influence your sleep-wake needs include medical conditions, medications,
stress, sleep environment, and what you eat and drink. Perhaps the greatest influence is
the exposure to light. Specialized cells in the retinas of your eyes process light and tell
the brain whether it is day or night and can advance or delay our sleep-wake cycle.
Exposure to light can make it difficult to fall asleep and return to sleep when awakened.
Night shift workers often have trouble falling asleep when they go to bed, and have
trouble staying awake at work because their natural circadian rhythm and sleep-wake
cycle is disrupted. In the case of jet lag, circadian rhythms become out of sync with the
time of day when people fly to a different time zone, creating a mismatch between their
internal clock and the actual clock.
Questions n/a